This invention relates in general to bags and, more particularly, to a multi-ply inflatable dunnage bag having a unique shape and construction and to a method of utilizing such a bag for shoring freight.
Dunnage bags of the type indicated are used between containers or pallets of freight in transporting vehicles to prevent shifting of the freight while in transit. Since such bags are subjected to repeated impact by the shifting freight, they must be of sound construction and have strong and durable closures.
In practice in recent years has been to utilize disposable, inflatable dunnage bags which may be deflated when the freight reaches its destination. Since such bags are used only once, the bags have been so constructed and formed as to minimize the cost thereof. Typically, such a dunnage bag is of rectangular configuration; is made for layers of kraft paper containing an inflatable plastic bladder, with the opposite ends of the bag formed with closures; and is used to ship a wide range of products from plywood to pet foods. When placed in the void between a shipper's lading and inflated with two to eight psi of compressed air, the bag exerts a strong force in either direction. This fills the void to prevent shifting during transit and provides an air cushion to help absorb shocks or vibrations.
An inflatable dunnage bag consists of two major assemblies. The first is the body of the bag, made of various plies of kraft paper. The paper supplies the strength to retain the air pressure and prevent stretching or enlarging of the bag walls as it is inflated. The second assembly is the plastic liner. This retains the volume of air and prevents leakage. The liner or air bladder is constructed of plastic film. The valve and liner ends must be carefully heat sealed to complete the airtight closure.
Common practice in the application of inflatable dunnage bags is to contact as much of the lading as possible without extending beyond the perimeter of the lading. Accordingly, both the height and width of the load is measured at the point where the bags are to be installed. These dimensions determine the number of bags needed. The bags are invariably of rectangular shape.
In operation, cross-wise and longitudinal shifting of the load mostly involves the upper part of the load because the combined frictional force between the lower part of the load and the vehicle floor, together with the weight of the upper part of the load on the lower part and the frictional force between the load and the walls of the vehicle, is sufficient to restrain or inhibit the lower part of the load from moving. In light of this load characteristic, I have determined that load compacting, cushioning, repositioning and enlarging can be achieved with an inflatable dunnage bag of triangular shape.